The beauty of building your own kayak is that you can customize most of the features to fit you. Cockpits can be adjusted in width and length as long as there is width to the kayak. Leg length should not be a factor, since you will place your bulkheads where you need them. Things to look at will be deck height for feet and if you do adjust cockpit, you will need to recalculate placement of the opening to coincide with center of bouyancy as set out in the design. For example, on my designs, the rear edge of the opening is 14 in. aft of COB which allows for room for the backrest which usually moves your position forward between 2-3 in. So if one was to lenghten the opening, they would need to move the cockpit opening forward slightly. Of course one might wish to be slightly aft of COB so that the bow is up more. It is all a matter of preferences
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